title: Tonic inhibition of allergic itch signaling by the descending noradrenergic system in mice.
abstract: We investigated whether the descending noradrenergic system regulates allergic itch. Mosquito allergy of the hind paw elicited biting, an itch-related response, in sensitized mice. The biting was inhibited by intrathecal clonidine and reversed by yohimbine, an α(2)-adrenoceptor antagonist. The biting was increased by intrathecal pretreatment with the catecholaminergic neurotoxin 6-hydroxydopamine and the α-adrenoceptor antagonist phentolamine but not the serotonergic neurotoxin 5,7-dihydroxytryptamine. We propose that α(2)-adrenoceptors are involved in the inhibition of allergic itch in the spinal cord and that the descending noradrenergic system exerts a tonic inhibition on the itch signaling. The serotonergic system may not be involved.
authors.affiliation: Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Gotoh
authors.forename: Yu
authors.initials: Y
authors.lastname: Omori
authors.forename: Tsugunobu
authors.initials: T
authors.lastname: Andoh
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kuraishi
mesh_terms: D000818:Animals; D001733:Bites and Stings / Q000503:physiopathology; D003000:Clonidine / Q000008:administration & dosage / Q000494:pharmacology*; D009033:Culicidae; D006633:Histamine Antagonists / Q000627:therapeutic use*; D006967:Hypersensitivity / Q000503:physiopathology*; D007278:Injections, Spinal; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology*; D009638:Norepinephrine / Q000502:physiology*; D011537:Pruritus / Q000503:physiopathology*; D011942:Receptors, Adrenergic, alpha; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology*; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology; D015016:Yohimbine / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D006633:Histamine Antagonists; D011942:Receptors, Adrenergic, alpha; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine; D009270:Naloxone; D003000:Clonidine; D009638:Norepinephrine